1. Field of the Invention
The present invention relates to a manufacturing method of an optical waveguide device for widespread use in optical communications, optical information processing and other general optics, and an optical waveguide device obtained thereby.
2. Description of the Related Art
In general, an optical waveguide for an optical waveguide device is constructed such that cores serving as a passageway for light are formed in a predetermined pattern on a surface of an under cladding layer, and such that an over cladding layer is formed so as to cover the cores. Such an optical waveguide is typically formed on a surface of a substrate such as a metal substrate and the like, and is manufactured together with the substrate to provide an optical waveguide device.
A conventional manufacturing method of such an optical waveguide device is as follows. First, as shown in FIG. 4A, an under cladding layer 2 is formed on a surface of a substrate 10. Then, as shown in FIG. 4B, a photosensitive resin for the formation of cores is applied to a surface of the under cladding layer 2 to form a photosensitive resin layer 3A. Next, irradiation light L is directed through a photomask M formed with an opening pattern corresponding to the pattern of the cores toward the above-mentioned photosensitive resin layer 3A. The irradiation light L is caused to reach the above-mentioned photosensitive resin layer 3A through openings of the above-mentioned opening pattern, thereby exposing portions of the photosensitive resin layer 3A thereto. The above-mentioned irradiation light L is directed to the above-mentioned photosensitive resin layer 3A at right angles thereto. A photoreaction proceeds in the portions exposed to the irradiation light L so that the exposed portions are hardened. Then, development is performed using a developing solution to dissolve away unexposed portions, as shown in FIG. 4C. The remaining exposed portions become cores 3 in a predetermined pattern. The cores 3 are typically formed to be rectangular in sectional configuration. Thereafter, as shown in FIG. 4D, an over cladding layer 4 is formed on the surface of the above-mentioned under cladding layer 2 so as to cover the cores 3. In this manner, an optical waveguide W is formed on the surface of the above-mentioned substrate (see, for example, Japanese Patent Application Laid-Open No. 2004-341454).